In recent years numerous studies have been carried out to define the biochemical significance of the polyamines spermidine and spermine and their precursor putrescine. Increased polyamine levels and synthesis have been found to occur in a number of systems characterized by a shift from a quiescent to a proliferating state. In vitro, the polyamines have been shown to stimulate DNA, RNA, and protein synthesis and have, thus, been implicated as being regulatory molecules involved in the metabolism of macromolecules in both procaryotes and eucaryotes. Nevertheless, the precise function of these cations in vivo remains obscure. High levels of methylated bases have also been shown to be affiliated with the onset of rapid cellular proliferation. S-Adenosylmethionine (SAM) serves as the propylamino donor in the synthesis of polyamines and as the methyl donor in transmethylation reactions. The overall objective of this proposal is to determine the SAM-related biochemical and genetic mechanisms associated with the initiation of mitosis. An excellent opportunity for studying the SAM-related molecular events necessary for the initiation of mitosis is provided by the germination and outgrowth of spores of Saccharomyces cerevisiae.